Intermittently variable feed mechanism for forming changeable lead helix



BRUEGGER INTERMITTENTLY VARIABLE FEED MECHANISM FOR June 25, 1957 E.

FORMING CHANGEABLE LEAD HELIX 4 Sheets-Sheet 1 Filed Feb. 23. 1954 %w@&'

ATTORNEYS I INVENTOR. Ernest Bra/eager BY June 25, 1957 E B EGGER2,796,794

.RU INTERMITTENTLY VARIABLE FEED MECHANISM FOR FORMING CHANGEABLE LEADHELIX Filed Feb. 23. 1954 4 Sheets-Sheet 2 INVENTOR. F09. 6 ErnesbBru/eg q'er ATTORNEYS June 25, 1957 E. BRUEGGER 2,796,794

INTERMITTENTLY VARIABLE FEED MECHANISM FOR FORMING CHANGEABLE LEAD HELIXFiled Feb. 23. 1954 4 Sheets-Sheet 3 (O In Fig 4 INVENTOR. Ernesfi Brweqyer ATTORNEYS June 25, 1957 E. BRUEGGER" 2,796,794

INTERMITTENTLY VARIABLE FEED MECHANISM FOR FORMING CHANGEABLE LEAD HELIXFiled Feb. 25, 1954 4 Sheets-Sheet 4 BY QWJ ATTORNEYS erally of lathetype.

United States Patent INTERMITTENTLY VARIABLE FEED MECHANISM FOR FoRMrNt;CHANGEABLE LEAD HELIX Ernest Bruegger, Massillon, Ohio, assignor to TheGris- .com-Russell Company, Massillon,.0hi0, a corporation of DelawareApp c t February 2 5 S r a N 411, 28

16 Claims. (CI. 32-41 The invention relates to apparatus forautomatically varying or changing the lead of a lathe lead screw invarious helical lathe operations wherein a helix iswound, formed or cutupon a cylinder or the like, and morepartigcularly to an automatic leadreducer in apparatus for winding a helical fin upon a tube orthe 'likejTubes for certain types of heat exchangers are provided with helicalfins which are wrapped or wound around the tubes and joined thereto on amachine gen- In the manufacture of such helical finned tubes, it isnecessary 'in certain locations along the length of the tube to providecollars or the like for supporting the tubes or for tying a plurality ofsuch tubes in bundles without collapsing or disturbing the normal finspacing generally throughout the length of the tubes by the weight ofthe other-tubes tied in the bundle.

Under present practice this has required stopping of the helical finapplying apparatus at intervals, cutting the fin material being applied,and performing some special operation at alparticular location, toprovide for the collar or support, after which the finning operationmust be resumed beyond the point where the collar or support isprovided.

The present invention contemplates ,the provision of means whereby thelead or spacing of the convol utions of a helix may be changedsubstantially automatically at any desired point or points along thelength thereof Another object is to provide means whereby thewlead orspacing of the convolutionsof a helical fin maybe thus automaticallychanged at any desired point ,along the length of the tube upon whichthe ;fin is being wrapped or wound, without stopping the operation ofthe machine,

and without cutting the fin material being applied to the tube, wherebyat desired locations the cohvolutions of the fins maybe locatedsubstantially in contact with each other or substantially bunched in asolid mass to act as a support collar upon the tube.

A further object is to provide neehanisgn ofthecharacter referred to inwhich a normally non-rotatable worm gear is mounted upon the carriage ofghe lathe Iilge machine and engages the lead screw inthe rnannerof aleadnot for normally advancin-gthe carriage uniiornrly from 'one-e nd of thelathe bed to the other, rneansbeing provided at one 'or more desiredlocations in the path of the carriage for automatically rotating theworm gear backward to reduce the leadrate,ofthecarriagedhereby th mbin ts n o u ou o thehelix rb r to tme at such point or points.

,Astil'l further object is .toprovide such mechanisrngin' which theworrngear is normallyiheld againstrotationby a friction clutch, and a I star,wheeh operatively. connected to the worm gear, is adaptedtoiberotatedat a;pre determined point or points in the ,travel .of the carrialge bymeans of a trippin locatedatsuch point or'p oint s.

Ano h bi p h t n t iq i t RKQY Q 1 uc m sh uism i wh ch th s u ss :icreat el s n ttd t h M ment haf -thr EQQ E QH fiQ and a friction brakeis provided upon such gear reduction for normally preventing rotation ofthe star wheel.

A further object is to provide means for forming a changeable leadhelical groove in a tube or the like, and means for guiding the finmaterial into said groove for forming a changeable lead helical fincorresponding to the helical groove.

A still further object is to provide means tor adjustab'ly mounting thetrip pin or pins at any desired point or points along the bed of themachine.

Stated in general terms, the invention comprises a machine, generally oflathe type, having a carriage slidable longitudinally thereon, acontinuously rotating leadscrew being journalled in the bed and a leadnut,'in the'form of a normally non-rotatable worm gear, being mountedupon the carriage and engaging the lead screw, the machine having aheadstock and tailstock in which a tube or other cylinder iscontinuously rotated, means being provided upon the carriage for cuttingand/or winding a helix upon the cylinder, trip means being provided atany desired point or points upon the bed of the machine for rotating theworm gear backward at such point or points to reduce the lead of thespiral being cut or formed upon the cylinder.

The above and other objects, apparent from the drawings and followingdescription, may be attained, the above described 'difiiculties overcomeand the advantages and results obtained, by the apparatus, construction,arrangement and combinations, sub-combinations and parts which comprisethe present invention, a preferred embodiment of which, illustrative ofthe best mode in which applicant has contemplated applying theprinciple, being set forth in detail in the following description an'dillustrated in the accompanying drawings, in which: i

Fig. l is a side elevation'of an embodiment of the invention comprisingapparatus for simultaneously coiling a metal ribbon and applying thesame onto a tube in the form of a helical -fin and intermittentlybunching the convolutions of the helical fin at spaced points on thetube;

Fig. 2 is a fragmentary, transverse view showing tool heads by means ofwhich the spiral groove is formed in the tube and the metal ribbon isspirally wound therepn;

Fig. 3 is an enlarged, fragmentary front elevation showing a portion ofthe bed, the carriage, a portion of the lead screw and means for varyingthe lead of the heliX; Fig. 4 is a fragmentary top plan view of theparts shown in Fig. 3, parts being shown in section;

Fig. 5 is a transverse section taken on the lined- 5,

Fig.6 is a fragmentary elevation of a po-rtion of a tube with helicalfin of variable lead shown thereon.

Referring now moreparticularly to the. embodiment of the invention shownin the drawings, in which similar numerals refer to similarpartsthroughout, the invention is illustrated as appliedto a machineformanufacture of finned tubing, of the general type of Dewald Patent No.

2,004,388 dated June 11, 1 935, and more particularly to the formthereof in which a metal ribbon is simultaneouslycoiled and applied toatube.

For this purpose a machine ofthe lathe type is illustrated, havingsupports for a bed 10, and atmotor or other source of power (not shown)for driving the headstock spindle 11 through gearing 12. The spindle 111is geared to a lead screw 13 through a train of gears 14. Twocooperating tool heads 15 and 16 arevrno unted on the carriage 17 andare adjustable toward and from each other in usual manner.

The 'tailstock 18 is adapted to be anchored at the desired point uponthe bed'10 by a set screw-19, and a tube to be :finned, as indicatedatT, is adaptedto be ,rotatably mounted between the headstock andtailstock roughening roll 23, and the tool head 16 carries the leadrolls 24 and the knurling rolls 25. All of the above parts may be of thegeneral construction as disclosed in said Patent No. 2,004,388.

The variable feed mechanism for varying or reducing the lead is shown indetail in Figs. 3 to inclusive, to which reference is now made. For thispurpose the conventional split lead screw nut is replaced by a worm.wheel 26 which is in constant engagement with the lead screw 13 andassumes the function of the conventional lead screw nut.

This worm wheel 26 is mounted upon the shaft 27, located transversely ofthe bed, and journalled at opposite ends in the brackets 28 and 29 whichare shown attached to the front and rear sides respectively of thecarriage 17 as by the cap screws 30. The shaft 27 is held againstlongitudinal movement relative to the carriage by the collars 31attached to opposite end portions of the shaft as by set screws 32, andcontacting the bushings 33 and 34 in the brackets 28 and 29respectively.

The worm wheel 26 has a free running fit upon the shaft 27, and isarranged to be normally locked upon the shaft by means of the clutchmechanism shown in detail. 1

in Figs. 4 and 5. This clutch mechanism includes the clutch drum member35, slidably keyed upon the shaft 27, as by the feather key 36, andprovided with the friction cone 37 engaged in the conical socket 38 inthe adjacent side of the worm wheel 26.

A collar 39 is fixed upon the shaft 27, as by a set i screw 40 and theworm wheel 26 is normally held in contact with said collar, whichpositions the worm wheel upon the shaft so as to hold it in constantengagement with the lead screw 13. For the purpose of normally holdingthe clutch cone 37 frictionally engaged with the worm wheel 26, apressure spring 41 is located upon the shaft 27 between the collar 42and the clutch member 36.

The collar 42 may be located upon the shaft at any desired position bymeans of the set screw 43 for placing the desired tension upon thepressure spring 41. The rear end portion of the shaft 26 is providedwith the axial bore 44, within which is longitudinally, slidably locatedthe clutch throw out rod 45 which carries the transversely disposed pin46 at its inner end located through the elongated diametric slots 47 inthe shaft 27 and fixed within the radial bore 48 in the hub 49 of theclutch member 35.

A clutch release knob 50 is rotatably mounted upon the outer end of theclutch throw out rod 45, as by the nut 51 and lock nut 52 located uponthe threaded outer end portion 53 of said rod. Clutch release show-pins54 extend inwardly from the release knob 50, and the inner ends thereofare normally received in recesses 55 in the outer end of the shaft 27.

Radial pins 56 may be provided in the release knob 50 to assist ingrasping the same in the hand to pull the clutch throw out rod 45outward in order to disengage the friction cone 37 from the worm wheel.

The knob 50 may be rotated relative to the rod 45 so that the ends ofthe show-pins 54 will engage the end of the shaft 27 at points spacedfrom the recess 55, thus holding the clutch released. The only time thatthis clutch is released by means of the release knob and show-pins asabove described is for freewheeling action of the carriage in eitherdirection upon the bed.

A reduction gear box 57 is'mounted upon the bracket 4 28. Within thisgear box is located the reduction pinion 58, fixed upon the adjacent endportion of the shaft 27 and mashing with the reduction gear 59. The gear59 is fixed upon the shaft 60, which is journalled in the gear box 57and has the braking hub 61 formed integral therewith.

The gears 58 and 59, together with the braking hub 61, are restrainedfrom rotation during the normal lead by pressure of the brake tensionscrews 62 upon the braking hub 61. These screws are set on the brakinghub just tightly enough to overcome the torque tendency produced in theworm wheel nut 26 by revolving action of the lead screw 13, andconsequently the entire lead screw reducing mechanism is normally lockedagainst rotation, or has only linear motion along the lead screw 13. Thereduction gears 58 and 59 are so computed that when they come intoaction they will produce a backward rotation of the worm wheel 26sufiicient to reduce the lead as desired. a

A star wheel 63 .is fixed upon the outer end of the reduction gear shaft60, on the outside of the gear box 57, as by the set screw 64 locatedthrough the hub 65 of the star wheel. A plurality of radially disposedspider trip legs 66, of suitable length and spacing, are fixed in theperiphery of the star wheel 63.

An angle gauge rail 67 is attached to the front side of the bed 10, asby screws 68, and extends the full length of the finning. capacity ofthe lathe. At one or more points along the angle gauge rail 67, where itis desired to reduce the lead, trip means may be mounted upon the rail67. i

As best shown in Figs. 3 and 5 this trip means may comprise a trip gaugeblock 69 having the horizontal slot 70, in its rear side for mountingupon the horizontal flange of the angle rail 67, a clamping screw 71being threaded in a suitable tapped bore 72 in the block for clamping itin adjusted position upon the rail.

A horizontally disposed trip pin 73 is carried by the trip gauge block69 and adapted to be normally located in the path of the trip legs 66 ofthe star wheel. This trip pin is located diametrically through the hub74 of the vertical shaft 75, journalled in the trip gauge block 69, andthe inner end 73a of the trip pin is normally held in contact with thetrip pin stop stud 76 by means of the trip pin return spring 77, whichis connected to the inner end portion 73a of the trip pin and to thetrip gauge block 69 as by the screw 78. v

With the carriage 17 moving along the bed 10 from left to right, asviewed in Figs. 1 and 3, when one of the trip legs 66 of the star wheel63 engages the trip pin 73 in a wiping action, additional torque istransmitted to the reducing gears 58 and 59 and braking hub 61,overcoming the torque resistanceset up by the tension screws 62, causinga backward or counter-clockwise rotation of the shaft 27 and worm wheel26 as viewed in Fig. 3.

This backward rotation of the worm wheel nut 26 subtracts from thenormal lead tendency of the lead screw 13, producing a correspondinglyreduced lead in the helix being formed by the lathe-like machine.

In the operation of the machine illustrated, for applying a metal ribbonR to a tube T in a spiral or helical chine by the knurling rolls 25, asdisclosed in Dewald Patent No. 2,004,388, above referred to, forming aspiral fin R with relatively wide spacingv at normal lead' as underconventional practice.

At thepoint or points 'where the trip fingers 73 are locatedlin thepathof the trip legs upon the star wheel 63, thelead will be automaticallyreduced by backward 'rotation of the worm gear nut 26 upon the leadscrew,

and as shown at R in Figs; 1 and 6, the lead maybe reduced toapproximately fin thickness during the time that the worm wheel is beingrotated backwardly, producing a substantially solid fin block or collarat this point, as shown.

The length of this reduced lead may be determined by shortening orlengthening the trip legs 66 of the star wheel as desired. As the starwheel moves out of contact with the trip finger 73, the rotation of theworm wheel 26 will be stopped and the worm wheel will again be lockedagainst rotation and the machine will resume normal operation withnormal lead, continuing to apply the normally wide spaced fin upon thetube, as indicated at R in Fig. 6.

Although the invention is illustrated and described as applied to aparticular type of machine for the manufacture of finned tubing, itshould be understood that the variable feed mechanism for varying thelead of a lathe lead screw is applicable to various helical latheoperations wherein it may be desirable to change the lead, whether it bein the wrapping of fins, winding of wire springs, cutting threads, ormachining a changeable lead helix on a cylinder, either straight ortapered, which would be adaptable to standard lathe practice.

In the foregoing description, certain terms have been used for brevity,clearness and understanding, but no unnecessary limitations are to beimplied therefrom beyond the requirements of the prior art, because suchwords are used for descriptive purposes herein and are intended to bebroadly construed.

Moreover, the embodiments of the improved construction illustrated anddescribed herein are by way of example, and the scope of the presentinvention is not limited to the exact details of construction.

Having now described the invention or discovery, the

construction, the operation, and use of preferred embodiments thereof,.and the advantageous new and useful results obtained thereby; the newand useful construction, and reasonable mechanical equivalents thereofobvious to those skilled in the art, .are set forth in the appendedclaims.

I claim:

1. A machine of the lathe type, comprising a bed, a carriage movablelongitudinally upon the bed, a lead screw journalled in the bed, meansfor rotating the lead screw, a normally stationary worm wheel on thecarriage and engaging the lead screw for moving the carriagelongitudinally at a uniform speed, and means located at predeterminedpoints in the path of the carriage for intermittently rotating the wormwheel to vary the speed of movement of the carriage.

2. A machine of the lathe type, comprising a bed, a carriage movablelongitudinally upon the bed, a lead screw journalled in the bed, meansfor rotating the lead screw, a normally stationary worm wheel on thecarriage and engaging the lead screw for moving the carriagelongitudinally at a uniform speed, and means located at predeterminedpoints in the path of the carriage for intermittently rotating the wormwheel backward to reduce the speed of movement of the carriage.

3. A machine of the lathe type, comprising a bed, means for supporting acylinder upon the bed, a carriage movable longitudinally upon the bed, atool upon the carriage, means for rotating the cylinder with respect tothe tool, a lead screw journalled in the bed, means for rotating thelead screw, a normally stationary worm wheel on the carriage andengaging the lead screw for moving the car-riage longitudinally forcausing the too] to form a helix upon the cylinder, and means located atpredetermined points in the path of the carriage for intermittentlyrotating the worm wheel to vary the lead of the helix.

4. A machine of the lathe type, comprising a bed, means for supporting acylinder upon the bed, a carriage movable longitudinally upon the bed, atool upon the carriage, means for rotating the cylinder with respect tothe tool, a lead screw journalled in the bed, means for form a helixupon the cylinder, and means located at predetermined points in the pathof the carriage for in termittently rotating the worm wheel backward toreduce the lead of the helix.

5. A machine of the lathe type, comprising a bed, a carriage movablelongitudinally upon the bed, a lead screw journalled in the bed, meansfor rotating the lead screw, a transversely disposed shaft -journalledon the carriage, means normally preventing rotation of said shaft, aworm wheel mounted upon the shaft and engaging the lead screw for movingthe carriage longitudinally at a uniform speed, and means located in thepath of the shaft for rotating said shaftat a predetermined point tovary the speed of movement of the carriage.

6. A machine of the lathe type, comprising a bed, a carriage movablelongitudinally upon the bed, a lead screw journalled in the bed, meansfor rotating the lead screw, a transversely disposed shaft journalled onthe carriage, means normally preventing rotation of said shaft, a wormwheel mounted .upon the shaft and engaging the lead screw for moving thecarriage longitudinally at a uniform speed, and means located in thepath of the shaft for rotating said shaft backward at a predeterminedpoint toreduce thespeed of movement of the carriage.

7.-A machine of the lathe type, comprising a bed, a

carriage movable longitudinally upon the bed, a lead screw journalledinthe bed, means for rotating the lead screw, a transversely disposedshaft journalled on .the carriage, means lnormally preventing rotationof said shaft, a worm wheel mounted upon the shaft and engaging the leadscrew for moving the carriage longitudinally at a uniform speed, astarwheel operatively connected tosaid shaft, and a trip pin located at apredetermined point-in the pathof the star wheel for rotating said shaftto vary .the speed of. movement of the carriage.

.8. A machine of the lathe .type, comprising a bed, a

carriage movable longitudinally upon the bed, a lead screw journalled inthe bed, means for rotating the lead screw, a transversely disposedshaft journalled on the carriage, means normally preventing rotation ofsaid shaft,

a worm Wheel mounted upon the shaft and engaging the lead screw formoving the carriage longitudinally at a uniform speed, a star wheeloperatively connected to said shaft, and a trip pin located at apredetermined point in the path of the star wheel for rotating saidshaft backward to reduce the speed of movement of the carriage.

9. A machine of the lathe type, comprising a bed, a carriage movablelongitudinally upon the bed, a lead screw journalled in the bed, meansfor rotating the lead screw, a transversely disposed shaft journalled onthe carriage, reduction gearing operatively connected to said shaft,brake means in the reduction gearing for normally preventing rotation ofthe shaft, a worm wheel mounted upon the shaft and engaging the leadscrew for moving the carriage longitudinally at a uniform speed, andmeans located in the path of the shaft for rotating the shaft at apredetermined point to vary the speed of movement of the carriage.

10. A machine of the lathe type, comprising a bed, a carriage movablelongitudinally upon the bed, a lead screw journalled in the bed, meansfor rotating the lead screw, a transversely disposed shaft journalled onthe carriage, reduction gearing operatively connected to said shaft,brake means in the reduction gearing for normally preventing rotation ofthe shaft, a worm wheel mounted upon the shaft and engaging the leadscrew for moving the carriage longitudinally at a uniform speed, a starwheel operatively connected to said reduction gearing, and a trip pinlocated at a predetermined point in the path of the star wheel forrotating said shaft to vary the speed of movement of the carriage.

.car'riage movable longitudinally upon the bed, a lead screw journalledin the bed, means for rotating the lead screw, a transversely disposedshaft 'journalled on the carriage, reduction gearing operativelyconnected to said shaft, brake means in the reduction gearing fornormally preventing rotation of the shaft, a worm wheel rotatable uponthe shaft, a clutch normally locking the worm wheel upon the shaft,means for releasing the clutch to permit free wheeling movement of thecarriage in either direction upon the bed, the worm wheel engaging thelead screw for moving the carriage longitudinally at a uniform speed,and means located in the path of the shaft for rotating the shaft at apredetermined point to vary the speed of movement of the carriage.

12. A machine of the lathe type, comprising a bed, a carriage movablelongitudinally upon the bed, a lead screw journalled in the bed, meansfor rotating the lead screw, a transversely disposed shaft journalled on'the carriage, reduction'gearing operatively connected to said shaft,brake means in the reduction gearing for normally preventing rotation ofthe shaft, a worm Wheel rotatable upon the shaft, a clutch normallylocking the worm wheel uponthe shaft, means for releasing the clutch topermit free wheeling movement of the carriage in either direction uponthe bed, the worm wheel engaging the lead screw for moving the carriagelongitudinally at a uniform speed, a star wheel operatively connected.to said reduction gearing, and a trip pin located at a predeterminedpoint in the path of the star wheel to vary the speed of movement of thecarriage.

13. A machine of the lathe type, comprising a bed, a carriage movablelongitudinally upon the bed, a lead screw journalled in the bed, meansfor rotating the lead screw, a normally stationary worm wheel on thecarriage and engaging the lead screw for moving the carriagelongitudinally at a uniform speed, a star wheel operatively connected tosaid worm wheel, and trip pins located at predetermined points in thepath of the star wheel for intermittently rotating the worm wheel tovary the speed of movement of the carriage.

'14. A machine of the lathe type, comprising a bed, a carriage movablelongitudinally upon the bed, a lead screw journalled in the bed, meansfor rotating the lead screw, a normally stationary worm wheel on thecarriage and engaging the lead screw for moving the carriagelongitudinally at a uniform speed, a star wheel operatively connected tosaid worm wheel, and trip pins located at predetermined points in thepath of the star wheel for intermittently rotating the worm wheelbackward to reduce the speed'of movement of the carriage.

15. A machine of the lathe type, comprising a bed, means for supportinga cylinder upon the bed, a carriage movable longitudinally upon the bed,a tool upon the carriage, means for rotating the cylinder with respectto the tool, a lead screw journalled in the bed, means for rotating thelead screw, a normally stationary worm wheel on the carriage andengaging the lead screw for moving the carriage longitudinally forcausing the tool to form a helix upon the cylinder, a star wheeloperatively connected to said worm wheel, and trip pins located atpredetermined points in the path of the star wheel for intermittentlyrotating the worm wheel to vary the lead of the helix.

16. A machine of the lathe type, comprising a bed, a carriage movablelongitudinally upon the bed, a lead screw journalled in the bed, meansfor rotating the lead screw, a normally stationary worm wheel on thecarriage and engaging the lead screw for moving the carriagelongitudinally at a uniform speed, and cooperating means on the carriageand at predetermined points in the path of the carriage for rotating theworm wheel to vary the speed of movement of thecarriage.

References Cited in the file of this patent UNITED STATES PATENTS398,871 Wersley Mar. 5, 1889 1,863,553 Berg June 14, 1932 2,035,283Schroeder Mar. 24, 1936

